The present invention relates to methods for microbiological control in the production of sugar from sugar-containing plant materials, and particularly relates to bacterial control in beet sugar processing.
Sugar (sucrose) and sugar products are primarily obtained from the vegetable raw materials, such as sugar beets and sugar cane, by mechanically disintegrating these plants and extracting, or pressing out, sugar-containing solutions from the plant parts. Sugar beet, cultivated Beta vulgaris, is a plant whose root contains a high concentration of sucrose.
Sugar beets, and other sugar-containing plants that are obtained from agricultural raw materials, are subject to microbiological decay through bacteria, yeasts, and fungi within certain temperature ranges, pH values, and concentration limits. There is a risk of infestation by microorganisms in food-technological processes related to sugar-containing plants, such as sugar beets, both during sugar production processing operations and during storage of raw, intermediate, and final products related to these operations. Microorganisms can degrade sugars contained in the raw materials and process materials to acids and gases to cause loss of sugar product, and/or cause elevated bacterial populations in the products. Microorganisms can influence the process negatively, not only by causing sugar losses, but also, for example, by causing pH drops and high lactic acid concentrations, which can affect other steps in the process (e.g., pressability of the pulp). Moreover, the process for the production of sugar from beets (or sugar cane) risks a microbial cleavage of the disaccharide sucrose into the monosaccharides glucose and fructose, which involves further disadvantages in addition to the immediate loss of sucrose, causing, for instance, a more intense coloration of the syrup, a higher need for alkalizing agents, and an increased amount of molasses.
At temperatures of less than about 50° C., the sugar-containing solutions can be subject to decay by all the microorganisms mentioned, i.e., bacteria, yeasts, and fungi. When extracting juices by thermal cell opening at temperatures above 50° C., only thermophilic bacteria typically are still capable of metabolic activity. The metabolic activity of the thermophilic bacteria can cause problems, and bacterial propagation (growth) can worsen the problems. An example of such a thermal extraction method is the widely-applied hot water extraction of sugar beets (“diffusing”), used in sugar production. In the sugar industry, formalin, dithio-carbamates, peracetic acid, ammonium bisulfate, and quaternary ammonium bases, have been used as antibacterial agents in juice flow or perishable intermediate products. These compounds may be relatively stable and remain in the treated materials and their products. For at least several years, the beet sugar processing industry has been using formaldehyde as a treatment agent. To control (thermophilic) bacterial action, for instance, the feed water to a diffuser in beet sugar processing has been dosed with formaldehyde. Formaldehyde is toxic and reduces the brightness of the white sugar product.
Thus, the present inventors determined that improved methods are needed for the sugar production industry, such as beet sugar processing, for the control of the microbiology, which does not adversely affect the brightness of white sugar or otherwise contaminate the sugar products, and which can be used as a potable-water approved technology to expand treatment opportunities and locations within a sugar production operation.